CBC · California Building Code

Fire Performance & Combustible Cladding Limits

This hub summarizes CBC Chapter 14 rules on combustible exterior cladding: area/height limits, NFPA‑based testing triggers, and the sections that govern compliance.

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Last reviewed: July 5, 2026

Overview

This hub covers the California Building Code requirements that control fire performance of exterior wall systems and limit use of combustible cladding — how much combustible cladding is permitted, when assemblies must be fire‑tested, and which test standards apply. Chapter 14 (Exterior Walls) sets the scope and performance approach for exterior wall coverings and assemblies, including limitations based on fire separation distance, radiant‑heat exposure and surface‑burning characteristics (§1401–§1403) . Key referenced test standards (for example NFPA 285, NFPA 268, ASTM E84/UL 723 and ASTM E1354) are adopted by reference for evaluating assemblies and materials .

Because exterior cladding can drive vertical and lateral fire spread, the CBC requires additional performance or testing where combustible components are present. The vertical/lateral flame‑propagation rules in §1402.5 trigger NFPA 285 for exterior wall assemblies that contain combustible coverings, insulation, or combustible water‑resistive barriers; combustible WRBs on Type I–IV buildings over 40 ft also require NFPA 285 unless they meet specific exceptions (§1402.5–§1402.6) . Limits on area and height for combustible exterior wall coverings (including the 10% area limit at close separations and the 40‑ft height cap) and ignition‑resistance test requirements are found at §1405.1.1 and related subsections, with a tabulated method to determine minimum fire separation distances based on tolerated radiant heat exposure .

Other specialized sections address particular systems: metal composite materials (MCM) have their own requirements and surface‑burning limits (§1406), EIFS and HPL systems are covered in §1407–§1408, and Chapter 7 contains the broader fire‑resistance and assembly requirements that interact with Chapter 14 provisions (§701–§705) file.

In this section

Code references

Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:

  • CBC § 1405.1.3 Medium relevance — show source text

    1405.1.3 Fireblocking. Where the combustible exterior wall covering is furred out from the exterior wall and forms a solid surface, the distance between the back of the exterior wall covering and the exterior wall shall not exceed 1 [5] / 8 inches (41 mm). The concealed space thereby created shall be fireblocked in accordance with Section 718. Exception: The distance between the back of the exterior wall covering and the exterior wall shall be permitted to exceed 1 [5] / 8 inches (41 mm) where the concealed space is not required to be fireblocked by Section 718.

    SECTION 1406—METAL COMPOSITE MATERIAL (MCM)

    1406.1 General. The provisions of this section shall govern the materials, construction and quality of metal composite material (MCM) for use as exterior wall coverings in addition to other applicable requirements of Chapters 14 and 16.

    1406.2 Exterior wall covering. MCM used as exterior wall covering or as elements of balconies and similar projections and bay and oriel windows to provide cladding or weather resistance shall comply with Sections 1406.4 through 1406.13.

    1406.3 Architectural trim and embellishments. MCM used as architectural trim or embellishments shall comply with Sections 1406.7 through 1406.13.

    [BS] 1406.4 Structural design. MCM systems shall be designed and constructed to resist wind loads as required by Chapter 16 for components and cladding.

    1406.5 Approval. Results of approved tests or an engineering analysis shall be submitted to the building official to verify compliance with the requirements of Chapter 16 for wind loads.

    1406.6 Weather resistance. MCM systems shall comply with Section 1402 and shall be designed and constructed to resist wind and rain in accordance with this section and the manufacturer’s installation instructions.

    1406.7 Durability. MCM systems shall be constructed of approved materials that maintain the performance characteristics required in Section 1406 for the duration of use.

    1406.8 Fire-resistance rating. Where MCM systems are used on exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the required fire-resistance rating is maintained.

    Exception: MCM systems that are part of an exterior wall assembly not containing foam plastic insulation and are installed on the outer surface of a fire-resistance-rated exterior wall in a manner such that the attachments do not penetrate through the entire exterior wall assembly, shall not be required to comply with this section.

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    EXTERIOR WALLS

    1406.9 Surface-burning characteristics. Unless otherwise specified, MCM shall have a flame spread index of 75 or less and a smokedeveloped index of 450 or less when tested in the maximum thickness intended for use in accordance with ASTM E84 or UL 723.

  • CBC § 2.1 Medium relevance — show source text
    agency BSC BSC-
    CG    		 SFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC
    Adopting agency BSC BSC-
    CG    		 SFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6
    Adopt entire chapter X X X X X
    Adopt entire chapter as
    amended (amended sections
    listed below)    		 X X X X X X X
    Adopt only those sections
    that are listed below    		 X X X
    Chapter / Section
    1401 X
    1402 X
    1402.2.1 X
    1403 X
    1404 X
    1404.1.2 X X X X X X X
    1404.3.3 X
    1405 X
    1406 X
    1407 X
    1408 X
    1411 X
    1412 X
    1413 X X X X X X X

    The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

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    14 EXTERIOR WALLS

    User notes:

    About this chapter: Chapter 14 addresses requirements for exterior walls of buildings. Minimum standards for wall covering materials, such as material performance and fire resistance, installation of wall coverings and the ability of the wall to provide weather protection are provided. This chapter also contains limitations on the areas and heights of combustible wall coverings based on fire separation distances, radiant heat exposure and surface burning characteristics.

  • CBC § 14-16 Medium relevance — show source text

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    EXTERIOR WALLS

    TABLE 1405.1.1.1.2—MINIMUM FIRE SEPARATION FOR COMBUSTIBLE EXTERIOR WALL COVERINGS Col2
    FIRE SEPARATION DISTANCE (feet) TOLERABLE LEVEL INCIDENT RADIANT HEAT ENERGY (kW/m2)
    5 12.5
    6 11.8
    7 11.0
    8 10.3
    9 9.6
    10 8.9
    11 8.3
    12 7.7
    13 7.2
    14 6.7
    15 6.3
    16 5.9
    17 5.5
    18 5.2
    19 4.9
    20 4.6
    21 4.4
    22 4.1
    23 3.9
    24 3.7
    25 3.5
    For SI: 1 foot = 304.8 mm, 1 Btu/H2 × °F = 0.0057 kW/m2 × K. For SI: 1 foot = 304.8 mm, 1 Btu/H2 × °F = 0.0057 kW/m2 × K.

    1405.1.2 Location. Combustible exterior wall coverings located along the top of exterior walls shall be completely backed up by the exterior wall and shall not extend over or above the top of the exterior wall.

    1405.1.3 Fireblocking. Where the combustible exterior wall covering is furred out from the exterior wall and forms a solid surface, the distance between the back of the exterior wall covering and the exterior wall shall not exceed 1 [5] / 8 inches (41 mm). The concealed space thereby created shall be fireblocked in accordance with Section 718. Exception: The distance between the back of the exterior wall covering and the exterior wall shall be permitted to exceed 1 [5] / 8 inches (41 mm) where the concealed space is not required to be fireblocked by Section 718.

    SECTION 1406—METAL COMPOSITE MATERIAL (MCM)

    1406.1 General. The provisions of this section shall govern the materials, construction and quality of metal composite material (MCM) for use as exterior wall coverings in addition to other applicable requirements of Chapters 14 and 16.

    1406.2 Exterior wall covering. MCM used as exterior wall covering or as elements of balconies and similar projections and bay and oriel windows to provide cladding or weather resistance shall comply with Sections 1406.4 through 1406.13.

    1406.3 Architectural trim and embellishments. MCM used as architectural trim or embellishments shall comply with Sections 1406.7 through 1406.13.

    [BS] 1406.4 Structural design. MCM systems shall be designed and constructed to resist wind loads as required by Chapter 16 for components and cladding.

    1406.5 Approval. Results of approved tests or an engineering analysis shall be submitted to the building official to verify compliance with the requirements of Chapter 16 for wind loads.

  • CBC § 803.5.1 Medium relevance — show source text

    803.5.1, 803.5.1.1

    268—22: Standard Test Method for Determining Ignitability of Exterior Wall Assemblies Using a Radiant Heat Energy Source

    1405.1.1.1, 1405.1.1.1.1, 1405.1.1.1.2, 2603.5.7

    275—22: Standard Method of Fire Tests for the Evaluation of Thermal Barriers

    508.4.4.1, 509.4.1.1, 1406.10.2, 1408.10.2, 2603.4

    276—23: Standard Method of Fire Test for Determining the Heat Release Rate of Roofing Assemblies with Combustible Above- Deck Roofing Components

    1508.1, 2603.3, 2603.4.1.5

    285—23: Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components

    718.2.6, 1402.6, 1406.10.3, 1408.10.4, 1511.6.2, 2603.5.5

    286— 24 : Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth

    402.6.4.4, 424.2, 803.1.1, 803.1.1.1, 803.11, 803.12, 803.13, 1406.10.2, 1408.10.3, 2603.7, 2603.9, 2604.2.4, 2614.4, 3105.3

    288—22: Standard Methods of Fire Tests of Horizontal Fire Door Assemblies Installed in Horizontal Fire Resistance-Rated Assemblies

    712.1.13.1

    289—23: Standard Method of Fire Test for Individual Fuel Packages

    402.6.2, 402.6.4.5, 424.2, 806.4

    409—22: Standard on Aircraft Hangars 412.3.6, Table 412.3.6, 412.3.6.1, 412.5.5

    418— 24 : Standard for Heliports

    412.7.4

    484—22: Standard for Combustible Metals

    426.1

    502—20: Standard for Road Tunnels, Bridges, and Other Limited Access Highways

    429

    652—19: Standard on the Fundamentals of Combustible Dust

    426.1

    654—20: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids

    426.1

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    REFERENCED STANDARDS

    655—19: Standard for the Prevention of Sulfur Fires and Explosions

    426.1

    664—20: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities

    426.1

    701—23: Standard Methods of Fire Tests for Flame Propagation of Textiles and Films

  • CBC § 1.2 Medium relevance — show source text

    1_||X||||||||||||||||||||||| |1403|||X|||||||||||||||||||||| |1404|||X|||||||||||||||||||||| |1404.1.2||||||||X|X|X|X|X||X|X|||||||||| |1404.3.3|||||||||||||||||||||X|||| |1405|||X|||||||||||||||||||||| |1406|||X|||||||||||||||||||||| |1407|||X|||||||||||||||||||||| |1408|||X|||||||||||||||||||||| |1411|||X|||||||||||||||||||||| |1412|||X|||||||||||||||||||||| |1413||||||||X|X|X|X|X||X|X||||||||||

    The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

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    14 EXTERIOR WALLS

    User notes:

    About this chapter: Chapter 14 addresses requirements for exterior walls of buildings. Minimum standards for wall covering materials, such as material performance and fire resistance, installation of wall coverings and the ability of the wall to provide weather protection are provided. This chapter also contains limitations on the areas and heights of combustible wall coverings based on fire separation distances, radiant heat exposure and surface burning characteristics.

    ICC code development note: Code change proposals to sections preceded by the designation [BS] will be considered by the IBC—Structural Code Development

    Committee during the 2025 (Group B) Code Development Cycle.

    SECTION 1401—GENERAL

    1401.1 Scope. The provisions of this chapter shall establish the minimum requirements for exterior walls, exterior wall assemblies, exterior wall coverings, exterior wall openings, exterior windows and doors, exterior soffits and fascias, and architectural trim.

    SECTION 1402—PERFORMANCE REQUIREMENTS

    1402.1 General. The provisions of this section shall apply to exterior walls, exterior wall coverings and components thereof.

    1402.2 Weather protection. Buildings shall be provided with a weather-resistant exterior wall assembly. The exterior wall assembly shall include flashing, as described in Section 1404.4. The exterior wall assembly shall be designed and constructed in such a manner as to prevent the accumulation of water within the exterior wall assembly by providing a water-resistive barrier behind the exterior veneer, as described in Section 1403.2, and a means for draining water that enters the assembly to the exterior. Protection against condensation in the exterior wall assembly shall be provided in accordance with Section 1404.3.

    Exceptions:

    1. A weather-resistant exterior wall assembly shall not be required over concrete or masonry walls designed in accordance with Chapters 19 and 21, respectively.
    2. Compliance with the requirements for a means of drainage, and the requirements of Sections 1403.2 and 1404.4, shall not be required for an exterior wall assembly that has been demonstrated through testing to resist wind-driven rain, including joints, penetrations and intersections with dissimilar materials, in accordance with ASTM E331 under the following conditions:
  • CBC § 1402.4 Medium relevance — show source text

    1402.4 Fire resistance. Exterior walls shall be fire-resistance rated as required by other sections of this code with opening protection as required by Chapter 7.

    1402.5 Vertical and lateral flame propagation. Exterior walls on buildings of Type I, II, III and IV construction that contain a combustible exterior wall covering, combustible insulation or a combustible water-resistive barrier shall comply with Sections 1402.5.1 through 1402.5.5, as applicable. Where compliance with NFPA 285 and associated acceptance criteria is required in Sections 1402.5.1 through 1402.5.5, the exterior wall assembly shall be tested in accordance with and comply with the acceptance criteria of NFPA 285.

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    1402.5.1 Combustible water-resistive barrier. Exterior walls containing a combustible water-resistive barrier shall comply with Section 1402.6.

    1402.5.2 Metal composite material (MCM). Exterior walls containing metal composite material (MCM) systems shall comply with Section 1406.

    1402.5.3 Exterior insulation and finish system (EIFS). Exterior walls containing an exterior insulation and finish system (EIFS) shall comply with Section 1407.

    1402.5.4 High-pressure decorative exterior-grade compact laminate (HPL) system. Exterior walls containing a high-pressure decorative exterior-grade compact laminate (HPL) system shall comply with Section 1408.

    1402.5.5 Foam plastic insulation. Exterior walls containing foam plastic insulation shall comply with Section 2603.

    1402.6 Water-resistive barriers. Exterior walls on buildings of Type I, II, III or IV construction that are greater than 40 feet (12 192 mm) in height above grade plane and contain a combustible water-resistive barrier shall be tested in accordance with and comply with the acceptance criteria of NFPA 285.Combustibility shall be determined in accordance with Section 703.3. For the purposes of this section, fenestration products, flashing of fenestration products and water-resistive-barrier flashing and accessories at other locations, including through wall flashings, shall not be considered part of the water-resistive barrier.

    Exceptions:

    1. Exterior walls in which the water-resistive barrier is the only combustible component and the exterior wall has an exterior wall covering of brick, concrete, stone, terra cotta, stucco or steel with minimum thicknesses in accordance with Table 1404.2.

    2. Exterior walls in which the water-resistive barrier is the only combustible component and the water-resistive barrier complies with the following: 2.1 A peak heat release rate of less than 150 kW/m [2], a total heat release of less than 20 MJ/m [2] and an effective heat of combustion of less than 18 MJ/kg when tested on specimens at the thickness intended for use, in accordance with ASTM E1354, in the horizontal orientation and at an incident radiant heat flux of 50 kW/m [2] .

    2.2 A flame spread index of 25 or less and a smoke-developed index of 450 or less as determined in accordance with ASTM E84 or UL 723, with test specimen preparation and mounting in accordance with ASTM E2404.

  • CBC § 1402.7 Medium relevance — show source text

    1402.7 Exterior wall veneers manufactured using combustible adhesives. Exterior wall assemblies on buildings of Type I, II, III or IV construction that are greater than 40 feet (12 192 mm) in height above grade plane and contain an exterior wall veneer manufactured using a combustible adhesive to laminate a metal core with noncombustible facing materials shall be tested in accordance with, and comply with, the acceptance criteria of NFPA 285, with the adhesive level at the maximum application rate intended for use. Combustibility shall be determined in accordance with Section 703.3.

    1402.8 Vertical and lateral flame propagation compliance methods. When exterior wall assemblies are required in this chapter to be tested for vertical and lateral flame propagation in accordance with and comply with the acceptance criteria of NFPA 285, compliance with the requirements shall be established by any of the following:

    1. An exterior wall assembly tested in accordance with and meeting the acceptance criteria of NFPA 285.
    2. An exterior wall assembly design listed by an approved agency for compliance with NFPA 285.
    3. An approved analysis based on an assembly or condition tested in accordance with and meeting the acceptance criteria of NFPA 285.

    [BS] 1402.9 Flood resistance. For buildings in flood hazard areas as established in Section 1612.3, exterior walls extending below the elevation required by Section 1612 shall be constructed with flood-damage-resistant materials.

    [BS] 1402.10 Flood resistance for coastal high-hazard areas and coastal A zones. For buildings in coastal high-hazard areas and coastal A zones as established in Section 1612.3, electrical, mechanical and plumbing system components shall not be mounted on or penetrate through exterior walls that are designed to break away under flood loads.

    SECTION 1403—MATERIALS

    1403.1 General. Materials used for the construction of exterior walls shall comply with the provisions of this section. Materials not prescribed herein shall be permitted, provided that any such alternative has been approved.

    1403.2 Water-resistive barrier. Not fewer than one layer of water-resistive barrier material shall be attached to the studs or sheathing, with flashing as described in Section 1404.4, in such a manner as to provide a continuous water-resistive barrier behind the exterior wall veneer. The intersection between the water-resistive barrier material and fenestration openings shall be flashed and assembled in accordance with the fenestration manufacturer’s installation instructions, or other approved methods for applications not addressed by the fenestration manufacturer’s instructions. The water-resistive barrier material shall be continuous to the top of walls and terminated at penetrations and building appendages in a manner to meet the requirements of the exterior wall envelope as described in Section 1402.2.

    Water-resistive barriers shall comply with one of the following:

    1. No. 15 felt complying with ASTM D226, Type 1.

    2. ASTM E2556, Type I or II.

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    1. Foam plastic insulating sheathing water-resistive barrier systems complying with Section 1402.2 and installed in accordance with manufacturer’s installation instructions.

    2. ASTM E331 in accordance with Section 1402.2.

    3. Other approved materials installed in accordance with the manufacturer’s installation instructions.

  • CBC § 0.019 Medium relevance — show source text

    Aluminum having a minimum thickness of 0.019 inch (0.5 mm). 2.2. Corrosion-resistant steel having a base metal thickness not less than 0.016 inch (0.4 mm) at any point. 2.3. Other approved noncombustible materials. 3. Fireblocking shall not be required where the exterior wall covering has been tested in accordance with, and complies with the acceptance criteria of, NFPA 285. The exterior wall covering shall be installed as tested in accordance with NFPA 285.

    718.2.7 Concealed sleeper spaces. Where wood sleepers are used for laying wood flooring on masonry or concrete fire-resistance-rated floors, the space between the floor slab and the underside of the wood flooring shall be filled with an approved material to resist the free passage of flame and products of combustion or fireblocked in such a manner that open spaces under the flooring shall not exceed 100 square feet (9.3 m [2] ) in area and such space shall be filled solidly under permanent partitions so that communication under the flooring between adjoining rooms shall not occur.

    Exceptions:

    1. Fireblocking is not required for slab-on-grade floors in gymnasiums.
    2. Fireblocking is required only at the juncture of each alternate lane and at the ends of each lane in a bowling facility.

    718.3 Draftstops in floors. Draftstops shall be installed to subdivide floor/ceiling assemblies where required by Section 708.4.3. In other than Group R occupancies, draftstops shall be installed to subdivide combustible floor/ceiling assemblies so that horizontal floor areas do not exceed 1,000 square feet (93 m [2] ).

    Exception: Buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1. 718.3.1 Draftstops material. Draftstops material shall be not less than [1] / 2 -inch (12.7 mm) gypsum board, [3] / 8 -inch (9.5 mm) wood structural panel, [3] / 8 -inch (9.5 mm) particleboard, 1-inch (25-mm) nominal lumber, cement fiberboard, batts or blankets of mineral wool or glass fiber, or other approved materials adequately supported. The integrity of draftstops shall be maintained.

    718.4 Draftstops in attics. Draftstops shall be installed to subdivide attic spaces where required by Section 708.4.3. In other than Group R, draftstops shall be installed to subdivide combustible attic spaces and combustible concealed roof spaces such that any horizontal area does not exceed 3,000 square feet (279 m [2] ). Ventilation of concealed roof spaces shall be maintained in accordance with Section 1202.2.1.

    Exception: Buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

    718.4.1 Draftstops material. Materials utilized for draftstops of attic spaces shall comply with Section 718.3.1.

    718.4.1.1 Openings. Openings in the partitions shall be protected by self-closing doors with automatic latches constructed as required for the partitions.

    718.5 Combustible materials in concealed spaces in Type I or II construction. Combustible materials shall not be permitted in concealed spaces of buildings of Type I or II construction.

    Exceptions:

    1. Combustible materials in accordance with Section 603.

    2. Combustible materials exposed within plenums complying with the California Mechanical Code .

  • CBC § 1402.6 Medium relevance — show source text

    1402.6 Water-resistive barriers. Exterior walls on buildings of Type I, II, III or IV construction that are greater than 40 feet (12 192 mm) in height above grade plane and contain a combustible water-resistive barrier shall be tested in accordance with and comply with the acceptance criteria of NFPA 285.Combustibility shall be determined in accordance with Section 703.3. For the purposes of this section, fenestration products, flashing of fenestration products and water-resistive-barrier flashing and accessories at other locations, including through wall flashings, shall not be considered part of the water-resistive barrier.

    Exceptions:

    1. Exterior walls in which the water-resistive barrier is the only combustible component and the exterior wall has an exterior wall covering of brick, concrete, stone, terra cotta, stucco or steel with minimum thicknesses in accordance with Table 1404.2.

    2. Exterior walls in which the water-resistive barrier is the only combustible component and the water-resistive barrier complies with the following: 2.1 A peak heat release rate of less than 150 kW/m [2], a total heat release of less than 20 MJ/m [2] and an effective heat of combustion of less than 18 MJ/kg when tested on specimens at the thickness intended for use, in accordance with ASTM E1354, in the horizontal orientation and at an incident radiant heat flux of 50 kW/m [2] .

    2.2 A flame spread index of 25 or less and a smoke-developed index of 450 or less as determined in accordance with ASTM E84 or UL 723, with test specimen preparation and mounting in accordance with ASTM E2404.

    1402.7 Exterior wall veneers manufactured using combustible adhesives. Exterior wall assemblies on buildings of Type I, II, III or IV construction that are greater than 40 feet (12 192 mm) in height above grade plane and contain an exterior wall veneer manufactured using a combustible adhesive to laminate a metal core with noncombustible facing materials shall be tested in accordance with, and comply with, the acceptance criteria of NFPA 285, with the adhesive level at the maximum application rate intended for use. Combustibility shall be determined in accordance with Section 703.3.

    1402.8 Vertical and lateral flame propagation compliance methods. When exterior wall assemblies are required in this chapter to be tested for vertical and lateral flame propagation in accordance with and comply with the acceptance criteria of NFPA 285, compliance with the requirements shall be established by any of the following:

    1. An exterior wall assembly tested in accordance with and meeting the acceptance criteria of NFPA 285.
    2. An exterior wall assembly design listed by an approved agency for compliance with NFPA 285.
    3. An approved analysis based on an assembly or condition tested in accordance with and meeting the acceptance criteria of NFPA 285.

    [BS] 1402.9 Flood resistance. For buildings in flood hazard areas as established in Section 1612.3, exterior walls extending below the elevation required by Section 1612 shall be constructed with flood-damage-resistant materials.

    [BS] 1402.10 Flood resistance for coastal high-hazard areas and coastal A zones. For buildings in coastal high-hazard areas and coastal A zones as established in Section 1612.3, electrical, mechanical and plumbing system components shall not be mounted on or penetrate through exterior walls that are designed to break away under flood loads.

    SECTION 1403—MATERIALS

  • CBC § 1409.7.3 Medium relevance — show source text

    1409.7.3 Type I, II, III, and IV construction. Where used as exterior walls or as exterior wall coverings on buildings of Type I, II, III and IV construction, IMP systems shall comply with this section as follows:

    1. IMP having a foam plastic core shall comply with Section 2603.5.
    2. IMP having combustible core other than foam plastic shall comply with Sections 1409.7.3.1 through 1409.7.3.4.

    1409.7.3.1 Surface-burning characteristics. A combustible core not greater than 4 inches (102 mm) in thickness shall have a flame spread index of 25 or less and a smoke-developed index of 450 or less when tested in the maximum thickness intended for use in accordance with ASTM E84 or UL 723. For thicknesses greater than 4 inches (102 mm) the combustible core shall have a flame spread index of 75 or less and a smoke-developed index of 450 or less at 4 inches (102 mm) in thickness and the IMP approved based on testing in accordance with Section 1409.7.2.2 at the maximum IMP thickness intended for use.

    1409.7.3.2 Thermal barrier. IMP shall be separated from the interior of a building by an approved thermal barrier in accordance with Section 1409.7.2.

    1409.7.3.3 Vertical and lateral flame propagation. IMP installations greater than 40 feet (12 192 mm) in height above grade plane shall be tested in accordance with and comply with the acceptance criteria of NFPA 285. Such testing shall be performed on the exterior wall assembly and with the IMP in the maximum thickness intended for use.

    1409.7.3.4 Ignition. IMP installations shall not exhibit sustained flaming where tested in accordance with NFPA 268. Where a material is intended to be installed in more than one thickness, tests of the minimum and maximum thicknesses intended for use shall be performed.

    Exceptions:

    Assemblies protected on the outside with one of the following:

    1. A thermal barrier complying with Section 1409.7.2.
    2. Concrete or masonry not less than 1 inch (25 mm) in thickness.
    3. Glass-fiber-reinforced concrete panels not less than [3] / 8 inch (9.5 mm) in thickness.
    4. Metal-faced panels having outer facings not less in thickness than 0.019 inch (0.48 mm) aluminum or 0.016 inch (0.41 mm) corrosion-resistant steel.
    5. Stucco not less than [7] / 8 inch (22.2 mm) in thickness, complying with Section 2510.
    6. Fiber-cement lap, panel or shingle siding complying with Section 1404.17 and Section 1404.17.1 or 1404.17.2, and having a thickness of not less than [1] / 4 inch (6.4 mm).

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    1409.8 Type V construction. IMP shall be permitted for use in Type V construction.

    1409.9 Labeling. Unless otherwise specified, the edge or face of each IMP or package shall bear the label of an approved agency. The label shall contain the manufacturer’s or distributor’s identification, model number, serial number or definitive information describing the product or materials’ performance characteristics and approved agency’s identification.

  • CBC § 1404.19 Medium relevance — show source text

    [BS] 1404.19 Fiber-mat reinforced cementitious backer units. Fiber-mat reinforced cementitious backer units shall be permitted on exterior walls and shall meet the requirements of Section 1404.19.1.

    [BS] 1404.19.1 Installation. Installation of fiber-mat reinforced cementitious backer units used as an exterior substrate for the application of exterior finish materials shall be in accordance with backer unit manufacturer’s installation instructions. Panels shall be installed using corrosion-resistant fasteners. Finish materials shall be installed in accordance with approved finish material manufacturer’s instructions.

    SECTION 1405—COMBUSTIBLE MATERIALS ON THE EXTERIOR SIDE OF EXTERIOR WALLS

    1405.1 Combustible exterior wall coverings. Combustible exterior wall coverings shall comply with this section.

    Exception: Plastics complying with Chapter 26.

    1405.1.1 Types I, II, III and IV-HT construction. On buildings of Types I, II, III and IV-HT construction, exterior wall coverings shall be permitted to be constructed of combustible materials, complying with the following limitations:

    1. Combustible exterior wall coverings shall not exceed 10 percent of an exterior wall surface area where the fire separation distance is 5 feet (1524 mm) or less.
    2. Combustible exterior wall coverings shall be limited to 40 feet (12 192 mm) in height above grade plane. Exceptions:
    3. Metal composite material (MCM) systems complying with Section 1406.
    4. Exterior insulation and finish systems (EIFS) complying with Section 1407.
    5. High-pressure decorative exterior-grade compact laminate (HPL) systems complying with Section 1408.
    6. Exterior wall coverings containing foam plastic insulation complying with Section 2603.
    7. Combustible exterior wall coverings constructed of fire-retardant-treated wood complying with Section 2303.2 for exterior installation shall not be limited in wall surface area where the fire separation distance is 5 feet (1524 mm) or less and shall be permitted up to 60 feet (18 288 mm) in height above grade plane regardless of the fire separation distance.
    8. Wood veneers shall comply with Section 1404.6.

    1405.1.1.1 Ignition resistance. Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.

    Exceptions:

    1. Wood or wood-based products.
    2. Other combustible materials covered with an exterior weather covering, other than vinyl sidings, included in and complying with the thickness requirements of Table 1404.2.
    3. Aluminum having a minimum thickness of 0.019 inch (0.48 mm).

    1405.1.1.1.1 Fire separation 5 feet or less. Where installed on exterior walls having a fire separation distance of 5 feet (1524 mm) or less, combustible exterior wall coverings shall not exhibit sustained flaming as defined in NFPA 268.

  • CBC § 2303.2 Medium relevance — show source text
    1. Combustible exterior wall coverings shall be limited to 40 feet (12 192 mm) in height above grade plane. Exceptions:
    2. Metal composite material (MCM) systems complying with Section 1406.
    3. Exterior insulation and finish systems (EIFS) complying with Section 1407.
    4. High-pressure decorative exterior-grade compact laminate (HPL) systems complying with Section 1408.
    5. Exterior wall coverings containing foam plastic insulation complying with Section 2603.
    6. Combustible exterior wall coverings constructed of fire-retardant-treated wood complying with Section 2303.2 for exterior installation shall not be limited in wall surface area where the fire separation distance is 5 feet (1524 mm) or less and shall be permitted up to 60 feet (18 288 mm) in height above grade plane regardless of the fire separation distance.
    7. Wood veneers shall comply with Section 1404.6.

    1405.1.1.1 Ignition resistance. Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.

    Exceptions:

    1. Wood or wood-based products.
    2. Other combustible materials covered with an exterior weather covering, other than vinyl sidings, included in and complying with the thickness requirements of Table 1404.2.
    3. Aluminum having a minimum thickness of 0.019 inch (0.48 mm).

    1405.1.1.1.1 Fire separation 5 feet or less. Where installed on exterior walls having a fire separation distance of 5 feet (1524 mm) or less, combustible exterior wall coverings shall not exhibit sustained flaming as defined in NFPA 268.

    1405.1.1.1.2 Fire separation greater than 5 feet. For fire separation distances greater than 5 feet (1524 mm), any exterior wall covering shall be permitted that has been exposed to a reduced level of incident radiant heat flux in accordance with the NFPA 268 test method without exhibiting sustained flaming. The minimum fire separation distance required for the exterior wall covering shall be determined from Table 1405.1.1.1.2 based on the maximum tolerable level of incident radiant heat flux that does not cause sustained flaming of the exterior wall covering.

    14-16 2025 CALIFORNIA BUILDING CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    EXTERIOR WALLS

Frequently asked questions

When does an exterior wall assembly need NFPA 285 testing?

Exterior wall assemblies must comply with NFPA 285 when §1402.5 applies — i.e., where the wall contains a combustible exterior covering, combustible insulation, or a combustible water‑resistive barrier on buildings of Type I, II, III or IV construction (with additional height triggers such as combustible WRBs on walls over 40 ft) §1402.5–§1402.6 . §1402.8 lists accepted compliance methods (test, listed design, or approved analysis) for meeting the NFPA 285 requirement .

What are the CBC area and height limits for combustible cladding?

On buildings of Types I–IV, combustible exterior wall coverings are limited so they do not exceed 10% of an exterior wall surface area where the fire separation distance is 5 ft or less, and combustible coverings are generally limited to 40 ft in height above grade plane, subject to enumerated exceptions (for example compliant MCM, EIFS, HPL, foam plastic rules, or fire‑retardant‑treated wood) — see §1405.1.1 and related subsections .

Which test methods and criteria should I expect to reference for cladding compliance?

The CBC references NFPA 285 for multi‑story vertical/lateral flame propagation, NFPA 268 for ignition resistance of combustible coverings, ASTM E84/UL 723 for surface‑burning characteristics, and ASTM E1354 (cone calorimeter) for heat‑release criteria in certain WRB exceptions; these standards are specifically cited in the referenced‑standards list and the Chapter 14 provisions that invoke them file.

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